"I noticed it today, maybe because the bike vibrates a lot, while riding my Royal Enfield (my) Misfit was counting the vibrates as steps. Does anyone else have this issue with Misfit? What are the other apps I can play around with to see if this happens with all of them?"

The Misfit website specifically says its monitor will count the number of times you pedal a bicycle. So it is pretty sensitive.

Vivek seems to consider this a problem, but I think some Royal Enfield owners will consider it a badge of honor.